Hello Nancy
I don't know anything about this family, although I suspect there could be a distant link between the Candy and the Parsons families in Trowbridge.
However, I wonder if the marriage was actually in Somerset instead of Wiltshire? It was common to marry in the wife's parish, and since Mary Taylor was from Bath, I wonder if that's where they married?
Going back to the 1841 Census, it looks as if the children in order were;
James (b ca 1829) Not born in Wales
Mary (b ca 1830) Not born in wales
Elizabeth (b ca 1832) Not born in Wales
Samuel (b ca 1835) Born in Wales
John (b ca 1839) Born in Wales
Henry (b ca 1841) Born in Wales
In 1861 there was also
Harriet (b ca 1843) Born in wales
Jane (b ca 1849) Born in Wales
So it looks as if they moved from England to Wales in about 1833 or 1834.
Back in England, the most likely birthplace would be Somerset or Wiltshire, and in 1861 Elizabeth is shown as Trowbridge, Wilts. It is interesting to note that their first(?) male child was named James (not Samuel) which suggests that this could be the name of Samuel's father back in Trowbridge.
If you can't find the marriage any other way, you could have a look at familyhistoryonline.net, where there is a marriage in Somerset in 1827 for a Samuel PARSONS and a matching entry for a Mary TAYLOR, although I don't know if they are a couple.
Good luck with your research.
Kind regards
Philip Candy